How Fructose makes you AGE.

By December 24, 2010Sugar

The fructose half of sugar causes irreversible cellular damage. And this damage may just be the thing which links most of the diseases of the Western World (oh, and makes us prematurely elderly as well). But there is a way to limit the damage. No its not a drug (although plenty of people are trying to find one). All you have to do is stop eating sugar.

Enzymes control chemical reactions in our body. If we need a sugar (like glucose or fructose) to be attached to a protein for some purpose, the appropriate enzyme will make sure the sugar gets attached to exactly the right part of the protein (or fat). The process of attachment is called glycosylation and we are only just beginning to understand the enormous array of uses our body has for glycosylated proteins (such as fending off disease and even inhibiting the development of Type II diabetes).

It is however possible for sugars to accidentally attach themselves to proteins without an enzyme’s help. When that happens, the process is called glycation. Glycation can result in sugars being attached in all sorts of unpredictable (and haphazard) ways.

Glycation happens by accident and is really only likely to happen when our blood sugar levels are high (the more sugar molecules there are floating around the more likely some of them are likely to crash into a protein). The good news is that in normal circumstances glycation is reversible. As soon as blood sugar levels drop, most of the sugars and proteins will disengage and no harm is done.

But if blood sugar stays high (as is the case with someone who is diabetic or pre-diabetic), the sugar-protein combo will undergo a series of reactions that will result in the creation of an Advanced Glycation End-product (AGE).

All sugars can form AGE’s, but the glucose half of sugar is the least reactive of all sugars. This is a good thing because it is the primary sugar in our bloodstream. The bad news is that the fructose half is ten times more reactive than glucose.

Eating sugar gives us a big shot of fructose and a big (and immediate) increase in AGE production. Making things much worse, fructose consumption also leads to an increase in insulin resistance. Over the long term the insulin resistance creates an environment where our blood glucose levels are persistently elevated. And this creates a second major source of AGE’s.

If your doctor suspects you of being diabetic, they will often test your HbA1c (or A1c for short) level. The test measures the level of a glycated form of haemoglobin (the protein which transports oxygen in your blood). A high A1c level indicates that there are significant AGE levels. That is taken as a sure sign that your blood sugar is persistently too high.

Our body’s are used to garden variety (glucose-produced) AGE’s. And we are pretty good at breaking them down and disposing of them. But even so, over time they accumulate in our organs and tissues and we, well, age (the acronym AGE is very much on purpose).

Unfortunately the AGE’s made with fructose molecules are resistant to our disposal system. So not only they made at 10 times the rate, they hang around like John Farnham on a comeback tour.

AGE’s are junk, litter on our body’s interstate highways. But this is not a burger wrapper chucked out the window. This is more like the (exploding) roadside litter our troops encounter in Afghanistan. AGE’s are dangerous because they bond easily (and randomly) to each other and to other proteins in a process called cross-linking.

AGE’s accumulate pretty much everywhere in the body, but in some places they do much more damage than others. When they pile up in the lens, cornea and retina of the eye they result in cataracts and macular degeneration (the leading cause of blindness in Australia). They also accumulate in the fine tubules of the kidneys – resulting in loss of kidney function.

They cross-link the collagen which otherwise gives our arterial walls (and our skin) their elasticity (hence the term, hardening of the arteries and the ‘aging’ of the skin). They cause the oxidation of LDL cholesterol particles, making them much more likely to become trapped in arterial walls (leading to heart disease and stroke). And they accumulate in the brain.

Neurons ideally last a lifetime. This means they are much more likely to accumulate AGEs. When researchers start looking at the tangles of twisted proteins which accumulate in the neurons of Alzheimer’s patients, they discover AGEs in abundance. This is likely to be the reason why other researchers have picked up on the association between Alzheimer’s (and other dementia) and high blood sugar.

Observational and controlled studies have linked fructose consumption to Type II Diabetes, Heart Disease, stroke, blindness, kidney disease and even Alzheimer’s (to name just a few of the more delightful ones). AGE research has come a long way in the last decade (and is still in its infancy), but it might just provide a unifying mechanism which explains why the incidence of these diseases is exploding in the Australian population – we eat way too much fructose.

So if aging slower (than you otherwise might) will be top of your to-do list in the New Year, you could buy a tub of hand cream sourced exclusively from the sweat of left-handed, French, mermaids – or you could just ease back on the fructose this Christmas.

Join the discussion 3 Comments

  • Jane Grey says:

    One of my Christmas presents was a book on how to live to 100, fit and alert. Unfortunately it involves a low-fat diet of lentils and manglewurzles (freshly dug from my own veggie patch) plus cold baths in a mountain stream if I can find one. I don’t fancy living to 100, but fit and alert sounds good. Maybe just staying off the fructose will do it. (I have some fine buttery, fructose-free biscuits – based on one of your recipes – baking right now.)

  • MGmirkin says:

    Finally, a layman’s English explanation of AGEs! Yay! Now I [sort of] understand!

  • Paul says:

    Crikey!! Reading about fructose is enough to cause premature aging.

    A lot of people argue that fructose must be safe because it is natural (at least when it hasn’t been industrially concentrated) and comes in fruit and berries.

    One thing worth remembering is that plants do not lace their fruit and berries because they think a sweet treat for humans is their duty. They make their fruit sweet to make it attractive to animals so that they will munch happily and then deposit the seeds sometime later away from the fruity/berry mothership.

    Making us eat the fruit is the mission. Keeping us healthy is not.

    Even if eating modest amounts of fruit were safe and that may not be a safe assumption for the reasons above, there is absolutely no reason to assume that industrial concentrations (sugar, juice, etc etc) of the sweetness that plants use to disperse their seeds is safe for human consumption.

    The burden on proof should be on those encouraging the consumption of industrially concentrated fructose.

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